The present invention relates to a novel vehicle headlamp apparatus. More particularly, the invention relates to a technique which ensures an optimum driving path illumination despite the existence of a leading vehicle and/or an oncoming vehicle.
Conventionally, in a vehicle such as an automobile, the illumination of a driving path is implemented by headlamps thereof, and beams used for light distribution of the headlamp are roughly classified into a high beam and a low beam.
The high beam is a beam for illuminating ahead mainly in a situation as found in a suburban area where there are fewer pedestrians and there exist near a subject vehicle no leading vehicle which drives ahead of the subject vehicle in the same driving direction and oncoming vehicle which drives in an opposite driving direction to that of the subject vehicle, as well as for illuminating as far as above an axis (referred to as an “optical axis at the normal time”) which passes through a center of the headlamp and extends in a longitudinal direction while kept parallel to a flat driving path in a normal state or in a state in which the subject vehicle is driving on the flat driving path in a normal condition or in a condition where the vehicle is inclined neither forward nor backward, whereby the high beam can illuminate a farther area of the driving path. On the other hand, the low beam is a beam used when the subject vehicle is driving in an urban area where there are many pedestrians, as well as in a situation where there exist leading vehicles and/or oncoming vehicles near the subject vehicle to illuminate ahead with no glare (dazzling light) being imparted to people near the subject vehicle or the drivers of the leading and oncoming vehicles and the pedestrians. The low beam has a cut-off line (an upper limit line) which extends substantially horizontally in the vicinity of or slightly below a line which horizontally extends across the optical axis at the normal time in a part of an illuminating range of the headlamp which is situated on a right side of the illuminating range in a transverse direction of the vehicle (the contour of the cut-off line of the low beam is such as to be applied to a case where left-hand driving is mandated, and in a case where right-hand driving is mandated, a contour is adopted which is symmetrically opposite to this contour in a transverse direction). Consequently, as long as the low beam is used, it is possible at the normal time to avoid such risks that an inside rearview mirror or an outside rearview of the leading vehicle is illuminated to thereby give a glare to the driver of the leading vehicle, that the driver of the oncoming vehicle is directly illuminated to thereby be given a glare, and that pedestrians are given a glare.
Then, the high beam and the low beam are switched over manually by the driver.
With the manual switching, however, there is case that switching is not implemented at an appropriate time, leading to another risk that people near the subject vehicle are given a glare (in the event that switching to the low beam is not implemented at a right time) or a risk that sufficient illumination is not provided ahead of the subject vehicle to thereby cause a problem of driving safety (in the event that switching to the high beam is not implemented at a right time)
Then, there has been proposed an automatic headlamp light distribution switching system in which the existence of leading and oncoming vehicles and distances from a subject vehicle to the leading and oncoming vehicles are detected based on image information captured by an image capture means and distance information captured by using a sensor such as a laser radar and a millimeter wave radar, respectively, whereby when there exist leading and oncoming vehicles within a predetermined distance range from the subject vehicle, switching to a low beam is carried out, whereas when there is no leading and oncoming vehicles within the predetermined distance range from the subject vehicle, the low beam is then switched to a high beam. By this construction, a case is avoided that the subject vehicle is driving with the headlamps set on high beam although there exist leading and oncoming vehicles or that only a road surface slightly ahead of the subject vehicle is illuminated although there exist no leading and oncoming vehicles and the subject vehicle is driving at high speed, thereby making it possible to ensure the safety of traffic.
However, with the aforesaid automatic headlamp light distribution switching system, although there is caused no problem while driving on a flat driving path or road, in a special driving condition, there is caused a problem that the safety of traffic is endangered by the automatic switching on the contrary.
As shown in FIG. 14, for example, with a subject vehicle “a” driving on a flat road, in the event that another vehicle “c” exists out of a detection area by a sensor “b” provided on the subject vehicle “a”, a high beam Hi is illuminated, and as a result, a glare is imparted to the driver of the other vehicle “c” and a pedestrian “d” who is difficult to be detected. This is a kind of problem that is caused by the capability of the sensor “b”, and there is a limit on a distance within which leading and oncoming vehicles can be detected. Even when the other vehicle “c” exists at an area beyond such a limit, the high beam Hi is directed toward the other vehicle “c”, and this may cause a risk that a glare is given to the driver of the other vehicle. Incidentally, when a low beam Lo is illuminated, due to the position of a cut-off line thereof there is caused no risk that a glare is given to the other vehicle “c” and the pedestrian “d”.
In addition, as shown in FIG. 15, when the subject vehicle “a” is climbing a hill, another vehicle “e” located on an opposite side of the hill to the subject vehicle “a” cannot be detected by the sensor “b” near the top of the hill, and hence the high beam Hi is illuminated. In this situation, when the other vehicle “e” suddenly appears at the top of the hill, the driver of the other vehicle “e” is hit with a glare.
Furthermore, when considering the driving safety of the subject vehicle, in both the cases illustrated in FIGS. 14 and 15, an area of the road surface which is located far ahead of the subject vehicle “a” cannot be illuminated with the low beam, and hence there is caused a problem with a high-speed driving. For example, in the case of FIG. 14, even in the event that a beam IL is emitted whose cut-off line IL cut exists at the detection limit position of the sensor “b”, there is caused no risk that the glare is given to the other vehicle “c” and the pedestrian “d”. In addition, in the case of FIG. 15, a road illumination up to the top of the hill which is a limit of the visional range of the driver of the subject vehicle can be achieved by emitting a beam IL whose cut-off line ILcut is positioned at the top of the hill, and even where the other vehicle “e” suddenly appears at the top of the hill, there is caused no risk that the driver of the other vehicle “e” is hit with the glare.